Although numerous studies have assessed the variability of aflatoxin production in several species of fungi, no studies on the genetics of aflatoxin production have been reported. The research program outlined in this proposal is designed to provide information concerning the genetic control of aflatoxin productiin in Aspergillus flavus. The broad objectives are as follows: 1. Determine the variability of aflatoxin B1, B2, G1 and G2 levels among wild-type and mutant isolates of A. flavus obtained from pecans. 2. Acquire auxotrophic and morphological mutants to serve as appropriate genetic markers. 3. Determine if levels of aflatoxin are genetically controlled. a. Synthesize heterozygous diploids (via heterokaroysis). b. Locate genes controlling aflatoxin production by demonstrating linkage to known genetic markers (via mitotic recombination). 4. Ascertain the role of possible polygenic effects.